Gastrocarcinogen N-methyl-N'-nitro-N-nitrosoguanidine is an antiandrogen

Kodama, Toshiko; Inoue, Fumio; Kodama, Mitsuo

doi:10.1016/0753-3322(89)90114-5

Cited by 8 publications

(14 citation statements)

References 4 publications

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“…The homogeneity is reflected in tight relations of observables such as Mg– σ 0 and Fe– σ 0 , and a clear correlation of [Fe/H] with the central velocity dispersion. The existence of the latter is reassuring in terms of our current understanding of the colour–magnitude relation (CMR) in clusters being mainly a result of increasing metallicity with increasing luminosity (Kodama & Arimoto 1997; Terlevich et al 1999).…”

Section: Discussionmentioning

confidence: 84%

“…However, both the 〈Mg〉– σ 0 and [Mg/H]– σ 0 relations are clearly seen in Coma. In this context it is important to note that the slope of the Fe– σ 0 relation which one would expect from the change of metallicity in the CMR (Kodama & Arimoto 1997) is quite shallow, and therefore only detectable with high S/N data. In contrast, the Mg– σ 0 relation is steeper, and therefore easier to detect.…”

Section: Discussionmentioning

confidence: 99%

“…In the conventional picture the global spectrophotometric relations observed for ellipticals, for example the colour–magnitude relation (Visvanathan & Sandage 1977; Bower, Lucey & Ellis 1992; Terlevich 1998), are explained by the steady increase in the abundance of heavy elements with increasing galaxy mass. This increase arises naturally in galactic wind models such as that of Arimoto & Yoshii (1987) and Kodama & Arimoto (1997).…”

Section: Introductionmentioning

confidence: 97%

“…Great efforts have been made in the last few years to develop evolutionary stellar population synthesis models (Bruzual & Charlot 1993; Worthey 1994, hereafter W94; Weiss, Peletier & Matteucci 1995; Vazdekis et al 1996, hereafter V96; Kodama & Arimoto 1997) in order to analyse the integrated light of galaxies and derive estimates of their mean ages and metal abundances. One of the main obstacles in the interpretation has been the age/metallicity degeneracy in old stellar populations.…”

Section: Introductionmentioning

confidence: 99%

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The stellar populations of early-type galaxies in the Fornax cluster

Küntschner

2000

Monthly Notices of the Royal Astronomical Society

289

508

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We have measured central line strengths for a magnitude‐limited sample of early‐type galaxies in the Fornax cluster, comprising 11 elliptical (E) and 11 lenticular (S0) galaxies, more luminous than MB=−17. When compared with single‐burst stellar population models we find that the centres of Fornax ellipticals follow a locus of fixed age and have metallicities varying roughly from half solar to twice solar. The centres of (lower luminosity) lenticular galaxies, however, exhibit a substantial spread to younger luminosity‐weighted ages, indicating a more extended star formation history. Galaxies with old stellar populations show tight scaling relations between metal‐line indices and the central velocity dispersion. Remarkably also, the Fe lines are well correlated with σ0. Our detailed analysis of the stellar populations suggests that these scaling relations are driven mostly by metallicity. Galaxies with a young stellar component do generally deviate from the main relation. In particular, the lower luminosity S0s show a large spread. Our conclusions are based on several age/metallicity diagnostic diagrams in the Lick/IDS system comprising established indices such as Mg2 and Hβ as well as new and more sensitive indices such as HγA and Fe3, a combination of three prominent Fe lines. The inferred difference in the age distribution between lenticular and elliptical galaxies is a robust conclusion, as the models generate consistent relative ages using different age and metallicity indicators, even though the absolute ages remain uncertain. The absolute age uncertainty is mainly caused by the effects of non‐solar abundance ratios which are not yet accounted for by the stellar population models. Furthermore, we find that elliptical galaxies and the bulge of one bright S0 are overabundant in magnesium, where the most luminous galaxies show the strongest overabundances. The stellar populations of young and faint S0s are consistent with solar abundance ratios or a weak Mg underabundance. Two of the faintest lenticular galaxies in our sample have blue continua and extremely strong Balmer‐line absorption, suggesting star formation <2 Gyr ago.

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Section: Discussionmentioning

confidence: 84%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

The stellar populations of early-type galaxies in the Fornax cluster

Küntschner

2000

Monthly Notices of the Royal Astronomical Society

289

508

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“…Given the degeneracy between the metallicity and age of a stellar population in its broad‐band colours, it is also possible that the CMR is an age‐driven sequence, with the smaller galaxies being bluer owing to a lower mean age of their stellar populations. An age‐dependent CMR however neither preserves its slope, nor its magnitude range with time (Kodama 1997; Kodama & Arimoto 1997). Studies of the CMR in high‐redshift clusters find a ridge‐line slope comparable to that of the local clusters; furthermore, there is no sign of a change in the range of magnitude over which the CMR may be traced (Ellis et al 1997; Stanford, Eisenhardt & Dickinson 1998).…”

Section: Introductionmentioning

confidence: 99%

Colour-magnitude relations and spectral line strengths in the Coma cluster

Terlevich

Küntschner

Bower

et al. 1999

Monthly Notices of the Royal Astronomical Society

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We use the C24668, Fe4383, HγA and HδA spectral absorption line indices, together with U‐ and V‐band photometry of 101 galaxies in the Coma cluster, to investigate how mean age and metal abundance correlate with galaxy luminosity. In particular, we use the line index measurements to address the origin of the colour–magnitude relation (CMR). We find that the CMR in Coma is driven primarily by a luminosity–metallicity correlation. We additionally show evidence for a relation between age and luminosity, in the direction predicted by the semi‐analytic hierarchical clustering models of Kauffmann & Charlot, but this is only present in the C24668 index models, and could be an effect of the lack of non‐solar abundance ratios in the Worthey models used. By comparing deviations from the CMR with deviations in absorption index from analogous ‘index–magnitude’ relations, we find that colour deviations bluewards of the mean relation are strongly correlated with the hydrogen Balmer line series absorption. We show that the properties of these blue galaxies are consistent with the presence of a young stellar population in the galaxies, rather than with a reduced metallicity.

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Tissue norepinephrine depletion as a mechanism for calcium chloride inhibition of gastric carcinogenesis in rats after treatment withN-methyl-N<?-nitro-N-nitrosoguanidine and sodium chloride

et al. 1996

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The effects of oral calcium chloride (CaCI2) on sodium chloride (NaCI)-enhanced induction of gastric carcinogenesis by the carcinogen N-methyl-N'-nitro-N-nitrosoguanidine, and the norepinephrine (NE) concentration in the gastric wall, were investigated in Wistar rats. Animals were given the carcinogen for 25 weeks and then chow pellets containing 10% NaCl with or without 8% or 4% CaCI2. In week 52, the incidence of gastric cancers, the N E concentration in the antral portion of gastric wall and the labelling index of antral epithelial cells were significantly greater in rats fed NaCl alone than in untreated control rats. Concomitant oral treatment with CaCI2 at 8%, but not 4%, significantly reduced the incidence of gastric cancers, the N E concentration in the antral portion of gastric wall and the labelling index of the antral epithelial cells in week 52 compared with those in rats fed NaCl alone. Because N E concentration reflects sympathetic nervous system activity, our findings suggest that the sympathetic nervous system could play a role in NaCI-enhanced gastric carcinogenesis. Our findings also suggest that N E depletion by CaCI2 may be related to its inhibition of NaC1-enhanced carcinogenesis.Q 1996 Wilqv-Liss. Inc.Sodium chloride (NaCI) has been proposed as an etiologic factor in gastric carcinogenesis in humans (Hirayama, 1968) and in rats (Ohgaki et al., 1984(Ohgaki et al., , 1989Shirai et al., 1984;Takahashi et aL, 1984 Takahashi et aL, , 1994Tatematsu et al., 1975Tatematsu et al., , 1989. Nishikawa et a/. (1992) examined the effects of calcium chloride (CaCI2) on gastric carcinogenesis induced by N-methyl-N'-nitro-N 4trosoguanidine (MNNG) and NaCl in Wistar rats. They found that both the incidence and number per rat of pre-neoplastic hyperplastic lesions after treatment with MNNG and NaCl followed by 1% or 0.2% CaClz were significantly lower than after MNNG and NaCl alone. However, the exact mechanism of the effects of NaCl and CaC12 remains unclear.A diet high in NaCl induces hypertension in Dahl saltsensitive rats. In these rats, the sympathetic nervous system contributes to elevation of arterial blood pressure (Haywood et al., 1985), and chemical sympathectomy with guanethidine or 6-hydroxydopamine prevents the development of hypertension (Friedman el al., 1979;Takeshita et al., 1979). Moreover, dietary Ca2+ intake influences the activity of the sympathetic nervous system in experimental animals (Hagihara et a/., 1991). These findings suggest that in MNNG-treated rats, a high-NaC1 diet might enhance gastric carcinogenesis, and CaC12 Supplementation might influence NaCl enhancement of carcinogenesis through the sympathetic nervous system. To test this possibility, we investigated the effect of a high-NaC1 diet with and without CaCI2 supplementation on gastric carcinogenesis in Wistar rats. MATERIAL AND METHODS AnimalsOne hundred fifty inbred male Wistar rats that initially weighed approximately 100 g were purchased from Japan SLC (Shizuoka, Japan). The animals were housed in suspended, wire-bo...

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Gastrocarcinogen N-methyl-N'-nitro-N-nitrosoguanidine is an antiandrogen

Cited by 8 publications

References 4 publications

The stellar populations of early-type galaxies in the Fornax cluster

The stellar populations of early-type galaxies in the Fornax cluster

Colour-magnitude relations and spectral line strengths in the Coma cluster

Tissue norepinephrine depletion as a mechanism for calcium chloride inhibition of gastric carcinogenesis in rats after treatment withN-methyl-N<?-nitro-N-nitrosoguanidine and sodium chloride

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